Torque tool with yielding drive



June 7, 1949. J. J. GREER TORQUE TOOL WITH YIELDING DRIVE Filed Feb. 8, 1945 ATTORNEYS Patented June 7, 1949 2372,6592 renown 'r'o'or. "wrrn "SE'IEBDINGDRIVE john i Greer, "Cofiimicut it nineteen rurua'ry s, wit, when zblaims. (ems-52.4)

tool of this character in which the amount'of ating values.

With these and other 'obj'ec'ts in view, the invention consists oi certain dveifesturs of construction, as will be more fully"described and particularly pointed out in the appended claims.

In the accompanying drawings:

,Fig. 1 is a longitudinal centra-l'sectional view of; -a screwdriver embodying the invention;

Fig'.;2 is a sectional view of-the handle r the screwdriver showing the relative position of several elements se'ciird thieto;

Fig. 3 is a perspective view of an assembly oi the elements shown attached to 'the handle in Fig. 2;

Fig. 4 is a perspective View of a support bearing member;

Fig. 5 is a perspective view of a portion of a spring through which torque is transmitted to the work;

Fig. 6 is a sectional view taken substantially along line 6--6 of Fig. 1;

Fig. '7 is an elevational view of a portion of the handle showing the window through which the torque value graduated scale may be viewed;

Fig. 8 is a top view of the tool with the cover of the handle removed; and

Fig. 9 is a view similar to that shown in Fig. 8 but showing one of the parts as having been rotated one quarter of a revolution.

In carrying out my invention as applied to a screwdriver I rotatably mount the handle and blade relative to each other and provide for the application of a yielding force to oppose relative rotation between the handle and the blade. This opposing :'force tin "the -instan't application is si'u'r n'ished byznieans t springs which arefingagd by the -'s'crewdriver' bladetor some element married by' tlfe blade. When aitorque producing vforce -is eippli'ed to'thehandle, bot'h handle and bladewill turn as a unit iuntlirthe torque applied exceeds 'inl'tl'ie opposing v'alueiof the-force furnished by the springs. Means are also provided whereby the effective leng-thof the springs may be varied-in order that variable values opposing the relative rotation between blaide and handle may be had,

Referring to thedraw-ings for a more detailed.

description "of the invention, l 5 designates genera-11y a screwdriver having--.-a blade -l6 to when is rotatably attached a handle I. The handle is hollow andis provided-atits upper end with asupport I8 (see,Fig.-=4) having :a central bearing opening +9 and oppositely disposed guide slots :20 which extendradially inwardly from the .peripheryofthe support.- The support [8 is snugly received withinthe bore 2i and is-s eated on an annular shoulder zi and is fastened in place by screw leolts"l3 Theshanlg fl of the blade {G -ifs vj ourn-aled-in-the opening 19 and 'has a-portionji thereof extending upwardly beyond the support. This portion 25 is reduced in size providingv a shoulder 26 and a non-circular extension which receives a cam member 21 made in the arm's:

an elong'ate d collar. This earn member has an opening to conform to the cross section of part 25 and rests 'oniuiesh umr 2s. The end Itrernity of the portidnzt is rip-set against the ollar 21- anu -securely fastens the same in place. The lowerpart of thehandl'e has an annular-rer imes- 28.111 Twh-i'ch'i's 'received a thrust bantearing 2'9. The outer 'race30 6f thebeariiig name secured to the wall of the recess in any approved manner and the inner race 3| to the shank 24. A collar'32 is secured to the shank by means of a pin 32 and provides an abutment against which the inner race 3| rests.

In order to oppose relative rotation between the handle and blade of the screwdriver, I provide fiat springs 33. These are positioned within the handle in a manner such as to be at a location opposite each other and extend lengthwise of the handle through the guide slots 20. The other ends of the springs 33 are anchored in the lower end of the handle by means of a support 34 which rests on the bottom of the hollow of the handle. The support is fastened in place by means of a screw bolt 35 extending through the handle and threadingly engaging the support 34. The support 34 is provided with a square opening 36 (see Fig. 3) which receives the ends of the springs 3 which are fastened to the walls of the opening by rivet pins 31 (see Fig. 1). The upper extremity of each spring is provided with a pad 38 which engages the cam 21.

As a torque producing force is applied to the handle, for transmission to the work, the handle and blade will turn as a unit until the torque applied exceeds the opposing value of the force furnished by the springs 33. This action may occur in either direction in which the torque is applied. In order that variable opposing values to the relative rotation between handle and blade may be had I provide for varying the effective length of the springs. This is accomplished by means of a collar 39 which has a squared opening 40 which embraces the springs 33, and which is movable lengthwise of the springs. The collar 39 is moved along the springs by means of a threaded member 4| which has a shank portion 42. This shank is journaled in a bearing opening 43 in the support IS. A handle 44 is provided for rotating the member 4| and forms a shoulder 45 with the shank 42. A coiled spring 46 encircles the shank 42 in the space between the shoulder 45 and support l3. A collar 41 is secured to the shank 42 and abuts against the lower surface of the support it. Thus, the member 4| is mounted for rotation in the opening 43 but is prevented from any substantial relative longitudinal movement therein.

The threaded portion of the member 4| is received in a threaded opening provided in the collar 39. Rotation of the member 4| will move the collar 39 lengthwise of the springs. When the collar is moved towards the free end of the springs the same will be stifiened to offer greater resistance to being spread apart to permit the cam 21 to rotate between the pads 38. When the collar is moved towards the anchored end of the springs the effective length of the springs will be increased and more resiliency will be provided.

Consequently, less force will be furnished by the springs on the cam 21 opposing relative rotation between handle and blade. Thus, this arrangement provides for presenting a choice of opposing values against relative movement between handle and blade.

In order to position the collar 39 at the proper location on the springs 33 so as to ofier an opposing force of a predetermined value, I provide a scale 48 which is properly graduated as at 49. This scale is fastened in a slot 50 in the collar 33 so as to move therewith. The handle is provided with a window through which the scale may be observed. A datum line 52 is enscribed on the handle for setting the collar at the proper location by means of the markings on the scale so as to provide an opposing force of the desired value. A cap 53 is telescopically received at the upper end of the handle and completes the assembly of the tool. In some instances the handle may be made of a transparent material and in which case the window 5| may be omitted and the scale observed through the material.

I claim:

1. In a torque tool, a work engaging member through which movement is transmitted to the work, a cam secured to said member, a handle rotatably mounted relative to said member and with the axis thereof extending coaxial with the axis of said member, spaced flat springs secured to said handle to move therewith and engaging said cam for opposing relative rotation between said handle and said member but moved apart by said. cam under certain pressure to permit relative rotation between handle and member, and a movable collar surrounding and engaging said springs and movable lengthwise thereof for varying the eiiective length of said springs.

2. In a torque tool, a screwdriver blade, a cam carried by said blade, a handle rotatably mounted relative to said blade, an elongated flexible and resilient member secured to said handle movable therewith and engagin said cam for opposing relative rotation between said handle and blade but flexed by said cam under certain pressure to permit relative rotation between handle and blade, and means movably mounted and engaging said flexible member between the point of engaging said cam and the point fixed to said. handle and movable lengthwise relative to said blade and handle along said member for varying the effective length of said flexible member.

JOHN J. GREER.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 2,205,510 Wolfram June 25, 1940 2,256,478 Hill Sept. 23, 1941 2,365,419 Lockheed Dec. 19, 1944 2,441,038 Siesel May 4, 1948 FOREIGN PATENTS Number Country Date 846,203 France May 2'7, 1939 

